For some reasons, 

My settings will cause kamailio to be restarted even if there were connections connected to it.

And when one SIP client in a connection wanted to hangup the call with a WebRTC Client (SIP over websocket) after the proxy-restarting,

local client was closed, however , the other side was not.

From the log below it seems that the connection missed.

Jan 30 18:19:31 ./kamailio[27857]: WARNING: <core> [msg_translator.c:2777]: via_builder(): TCP/TLS connection (id: 0) for WebSocket could not be found

Jan 30 18:19:31 ./kamailio[27857]: ERROR: tm [t_msgbuilder.c:1365]: assemble_via(): assemble_via: via building failed

Jan 30 18:19:31 ./kamailio[27857]: ERROR: tm [t_msgbuilder.c:1545]: build_uac_req(): build_uac_req(): Error while assembling Via

Jan 30 18:19:31 ./kamailio[27857]: ERROR: tm [uac.c:379]: t_uac_prepare(): t_uac: Error while building message

So,

Is it equivalent to connection ID missing?

And is there any way to make Websocket  found the connection?

Btw, after proxy-restarting for seconds , I typed `sh kamctl stats` :

websocket:ws_current_connections = 1

It showed that the WebRTC Client will re-connect automatically,

So I think this connection could be found by proxy,

Any suggestion?

Thanks :)